Support the use of --infotext when --buttonstyle stack is used

[philipross]

FR opened from previous issue raised: https://github.com/swiftDialog/swiftDialog/issues/511

Is your feature request related to a problem? Please describe. Currently, when using --buttonstyle stack it's not possible to also use --infotext and have the text display.

Describe the solution you'd like It would be really useful to have a small area, just above the buttons, that can be used to display info text when using buttons in a stacking style.

Describe alternatives you've considered N/A

Additional context Screenshots included of current state. /usr/local/bin/dialog --title none --messagealignment centre --messageposition centre --message "### Movie night! \n\nI'm not actually running a movie night, it's just to get your attention.\n\nSorry if that's disappointing, but you won't like my taste in films." --button1text "Sad times, I was looking forward to it! " --button2text "Phew, that was a close call..." --ontop --moveable --height 510 --width 400 --centreicon --icon SF=popcorn.circle,colour=auto --iconsize 130 --infotext "Here's some info" --buttonstyle stack

/usr/local/bin/dialog --title none --messagealignment centre --messageposition centre --message "### Movie night! \n\nI'm not actually running a movie night, it's just to get your attention.\n\nSorry if that's disappointing, but you won't like my taste in films." --button1text "Sad times, I was looking forward to it! " --button2text "Phew, that was a close call..." --ontop --moveable --height 510 --width 400 --centreicon --icon SF=popcorn.circle,colour=auto --iconsize 130 --infotext "Here's some info"

If that "Here's some info" was shown aligned to the left hand edge of the buttons, just above the button area, that would be 💯

[bartreardon]

This is similar to #486